1. Field of the Invention
The present invention relates to a power semiconductor module having a housing and low parasitic inductance half-bridge circuitry. More specifically, the present invention relates to half-bridge circuits having a first (TOP) and a second (BOT) power switch with each power switch being comprised of at least one power transistor and at least a corresponding power diode, a so-called recovery diode.
2. Description of the Related Art
The related art is reflected in DE 39 37 045 A1 and DE 100 37 533 C1. DE 39 37 045 describes a circuitry for a half-bridge for reducing parasitic inductance in the direct current leads. The two direct current leads are arranged in close proximity to each other, however, with the alternating current lead between plus and minus lead, and at least partially parallel with regard to each other. This design results in a reduction of the area that is surrounded by current in the area of the arrangement of the leads with close proximity and thus in relatively low inductance of this section of the leads.
DE 39 37 045, however, does not achieve the objective of obtaining minimal parasitic inductance for two major reasons.
First, the direct current leads are not arranged at a minimum distance with regard to each other since the alternating current lead is arranged between the two direct current leads. Thus the area surrounded by current in the area of the direct current lead is not minimal and therefore the inductance for this area is not minimal either.
Secondly, the first and the second power switches are arranged relatively far from each other, which also increases parasitic inductance.
DE 100 37 533 C1 discloses a more modern, very elaborate, but also very effective circuitry for reducing parasitic inductance. Here, all areas surrounded by current within a power semiconductor module are minimized to the greatest degree possible. The disadvantage is the considerably elaborate design and manufacture of such an embodiment of a power semiconductor module.
All power semiconductor modules according to the conventional state of the art have an alternating voltage output per half-bridge circuit. Unfortunately, this is disadvantageous, if the outside wiring of the power semiconductor module is to be different based on whether the current flows via the first (TOP) or the second (BOT) branch of the respective half-bridge.
Referring now to FIGS. 1A and 1B, a schematic view of the conventional art of power semiconductor modules with half or three-phase bridge circuitry is provided.
FIG. 1A shows a schematic view of a power semiconductor module with a housing 30. Arranged in the housing are a first (TOP) and a second (BOT) power switch. Respective power switches are comprised of at least one power transistor 10, 12, preferably a IGBT (insulated gate bipolar transistor) and at least an anti-parallel recovery diode 20, 22 and in which the respective transistors and corresponding recovery diodes are arranged in close proximity to each other.
The TOP switch is connected to a positive polarity direct current lead 40 and the BOT switch is connected to a negative polarity direct current lead 50. Both switches furthermore are connected to each other and an alternate current lead 60.
FIG. 1B shows another power semiconductor module with a related housing. In the module shown, three half-bridge circuitries are arranged in parallel, and form a three-phase bridge circuit.
Each of these half-bridges has the same arrangement as described above in FIG. 1A, but in three. For example, power transistors 10 and 12 are now power transistors 10a, 10b, and 10c and 12a, 12b, and 12c, respectively, and recovery diodes 20, 22 are now 20a, 20b, 20c and 22a, 22b, and 22c, respectively.
Additionally, the respective TOP switches are connected to the positive polarity direct current 40 and the respective BOT switches are connected to the negative polarity direct current lead 50. As shown, each half-bridge circuit is now connected with its own alternate current lead 60a, 60b, and 60c respectively that leads out from housing 30.
As noted earlier, what is not appreciated by the prior art is the need for the specific and simple circuitry provided by the present invention that overcomes each of the detriments noted above.
Accordingly, there is a need for an improved power semiconductor module with reduced parasitic inductance, can be easily manufactured, and in addition allows for flexible wiring of alternating current output lines.